This invention relates to laryngeal mask assemblies and their manufacture
It is common practice to use an airway known as a laryngeal mask for administering anaesthetic and ventilation gases to a patient. These airways comprise a tube with an inflatable mask or cuff at one end, the tube being inserted in the patient""s mouth so that one end is located in the hypopharynx and so that the mask forms a seal in this region with the surrounding tissue. Laryngeal masks are described in, for example, U.S. Pat. No. 5,355,879, U.S. Pat. No. 5,305,743, U.S. Pat. No. 5,297,547, U.S. Pat. No. 5,282,464, GB 2267034, U.S. Pat. No. 5,249,571, U.S. Pat. No. 5,241,956, U.S. Pat. No. 5,303,697, GB 2249959, GB 2111394, EP 448878, U.S. Pat. No. 4,995,388, GB 2205499, GB 2128561, GB 2298797, GB 2334215, GB 0020274 and GB 0002805.
Laryngeal masks have several advantages over endotracheal tubes, which are longer and seal with the trachea below the vocal folds. One potential problem with laryngeal masks is that there is a risk that they may be blocked by the epiglottis during insertion.
It is an object of the present invention to provide an alternative laryngeal mask assembly.
According to the present invention there is provided a laryngeal mask assembly comprising a tube, a mask at the patient end of the tube, an annular cuff extending around the patient end of the mask, and an internal cavity within the mask communicating with the tube at one end and opening from the assembly at its other end within a central region of the cuff, the assembly including blocking means that can be put in a first state where it prevents entry of the epiglottis into the cavity or a second state where the cavity is substantially open.
The blocking means may be an expansible member that is expanded in the first state and is retracted in the second state. The expansible member may be a balloon of an elastic material. The expansible member may be attached with the mask and communicate with an inflation lumen extending along the mask and tube. Alternatively, the blocking means could include a removable member such as a web extending across the patient end of the assembly. The removable member may be retained at its patient end with the mask by a rupturable joint and the assembly may include a non-elastic cord by which the rupturable joint can be torn from the machine end of the assembly. Alternatively, the removable member may be an insert extending along the tube, the insert having a portion expanded within the cavity, which portion provides an end surface substantially level with the patient end of the mask. The insert preferably includes a foam or gel. The mask preferably includes a mount on which the cuff is supported, and the assembly preferably has a region towards the mount that is resiliently flexible.
A laryngeal mask assembly according to the present invention will now be described, by way of example, with reference to the accompanying drawings.